title: Mapping the spatial and temporal progression of human dental enamel biomineralization using synchrotron X-ray diffraction.
abstract: OBJECTIVE
  The complex biological, physicochemical process of human dental enamel formation begins in utero and for most teeth takes several years to complete. Lost enamel tissue cannot regenerate, therefore a better understanding of the spatial and temporal progression of mineralization of this tissue is needed in order to design improved in vivo mineral growth processes for regenerative dentistry and allow the possibility to grow a synthetic whole or partial tooth.
  
  
  METHODS
  Human dental enamel samples across a range of developmental stages available through archaeological collections have been used to explore the spatial and temporal progression of enamel biomineralization. Position sensitive synchrotron X-ray diffraction was used to quantify spatial and temporal variations in crystallite organization, lattice parameters and crystallite thickness at three different stages in enamel maturation. In addition X-ray microtomography was used to study mineral content distributions.
  
  
  RESULTS
  An inverse correlation was found between the spatial variation in mineral content and the distribution of crystallite organization and thickness as a function of time during enamel maturation. Combined X-ray microtomography and synchrotron X-ray diffraction results show that as enamel matures the mineral content increases and the mineral density distribution becomes more homogeneous. Starting concurrently but proceeding at a slower rate, the enamel crystallites become more oriented and larger; and the crystallite organization becomes spatially more complex and heterogeneous.
  
  
  CONCLUSIONS
  During the mineralization of human dental enamel, the rate of mineral formation and mineral organization are not identical. Whilst the processes start simultaneously, full mineral content is achieved earlier, and crystallite organization is slower and continues for longer. These findings provide detailed insights into mineral development in human dental enamel which can inform synthetic biomimetic approaches for the benefit of clinical dentistry.
authors.affiliation: Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Simmons
authors.forename: Janet
authors.initials: J
authors.lastname: Montgomery
authors.forename: Julia
authors.initials: J
authors.lastname: Beaumont
authors.forename: Graham R
authors.initials: GR
authors.lastname: Davis
authors.forename: Maisoon
authors.initials: M
authors.lastname: Al-Jawad
mesh_terms: D000885:Anthropology, Physical / Q000379:methods*; D018360:Crystallography, X-Ray; D003743:Dental Enamel / Q000737:chemistry / Q000000981:diagnostic imaging / Q000254:growth & development*; D017886:Durapatite / Q000737:chemistry*; D006801:Humans; D017356:Synchrotrons; D014074:Tooth Calcification / Q000502:physiology*; D055114:X-Ray Microtomography
chemical_list: D017886:Durapatite
keywords: Biomineralization; Enamel; Hydroxyapatite; Preferred orientation; Synchrotron X-ray diffraction; Texture